At present, as shown in FIG. 1, an organic light emitting diode (OLED) pixel driving circuit generally contains a transistor T11, a transistor T12, a storage capacitor C11 and various drive signals for driving the OLED. A specific circuit connection is shown in FIG. 1. A working process of the pixel driving circuit comprises stages as follows.
In the signal write-in stage, in the case that a scan signal Scan is at high-level, the transistor T12 is switched on, a data signal Data is input to a gate electrode of the transistor T11 through the transistor T12, hence the transistor T11 is switched on and a capacitor C11 is charged.
In the light emitting stage, the scan signal Scan is made to be at low-level, the transistor T12 is switched off, the capacitor C11 is discharged to enable the transistor T11 to be still on. A power supply voltage PVDD keep providing the OLED with a voltage until a next stage arrives. The above cycle is then repeated.
However, due to a limitation of a process level, during a process of manufacturing a transistor circuit of an OLED display, a drive current of the OLED display often deviates and a panel often displays abnormally due to a threshold voltage existed in a driving transistor.